The goal of year 10 will be to isolate and compare the keratin polypeptides isolated from human skin. These peptides will be compared with peptides isolated from the same tissue and from other human epithelia. Keratin polypeptides from human skin and cervix will be purified by acrylamide slab gel electrophoresis. The polypeptides will be isolated by elution and constituent peptides produced by staphylococcus aureus protease, chymotrypsin, and cyanogen bromide will be compared. Pulse chase experiments utilizing the precursors leucine, histidine and cystine will provide information on 1: possible precursor product relationship between the various polypeptides; 2: changing patterns of labelling in cultivated human keratinocytes. Attached and shed cells will be compared. The pulse chase experiments will provide information on non-keratin proteins synthesized in these cultures. In particular we are looking for protein such as stratum corneum basic protein that are involved in the assembly of keratin filaments.